The present invention relates generally to the field of paint spray devices, and more particularly to a new arrangement for retaining a splash plate or deflector in a rotary bell cup.
The number of painting and coating devices are known and have been developed for a range of applications. These include devices that feed paint or other fluid coating materials through a base unit towards an atomizing bell cup. The bell cup is an assembly that is attached to a hollow shaft that rotates in the front of the base. The base is commonly referred to as an atomizer, and often includes an air-driven turbine that may spin at high speeds, typically from 30,000 to 70,000 RPM and above. During operation, the coating material is advanced through the atomizer and into the bell cup assembly. The coating contacts a splash plate or deflector that causes the fluid to be dispersed along the inner surface of the rotating bell cup. Various forms of bell cups are known and are presently in use, often fashioned for different types of paints, coatings, and so forth. The fluid exits an annular area between the splash plate and the bell cup inner surface and flows along the bell cup to an edge from which it is propelled. The bell cup assembly may be charged, or electrodes around the atomizer may charge the paint or coating material to cause it to flow under the influence of static charge towards an oppositely charged workpiece.
Although the particular form of bell cups used in such devices varies, it is typical to provide a splash plate assembly that is fitted into an aperture formed in the base of the bell cup. This assembly is often inserted into the aperture and retained in the aperture by a retaining ring arrangement. A typical conventional arrangement of this type is illustrated in FIG. 4. As shown in this figure, the bell cup C receives an insert I to which the splash plate SP is secured. The splash plate SP may be secured to an insert I by means of pins P, that also serve to space the splash plate from the insert. The insert I has an annular groove G formed around its periphery. A retaining ring R is snapped into this groove and pressed into engagement with a shoulder inside the bell cup as the splash plate and insert are placed in the receiving aperture during assembly.
In this arrangement, as the pins P are pressed into openings in the splash plate and insert provided for this purpose, the openings tend to deform the radially inner surface or floor of the groove G. When this occurs, the groove may require remachining to remove the deformity. Moreover, the retaining ring R inserted into this groove extends radially, and given the deformation, may extend radially too far out of the groove in the areas of such deformity. The retaining ring may be damaged or sheered off during pressing of the splash plate assembly into the bell cup. This may result in the splash plate assembly not being sufficiently robustly assembled into the bell cup to withstand the forces to which the bell cup is exposed in use.
There is a need, therefore, for improved rotary bell cup and splash plate assembly designs. In particular, there is a need for an arrangement that can avoid the problems associated with retaining rings conventionally used in designs of the type discussed above.